Long-term trends in atmospheric concentrations of
a
- and
g
-HCH in
the Arctic provide insight into the effects of legisl ation and climatic
fluctuations on contaminant levels
S. Becker
a
, C.J. Halsall
a
,
*
,W.Tych
a
, R. Kallenborn
b
,Y.Su
c
, H. Hung
c
a
Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
b
Norwegian Institute for Air Research (NILU), PO Box 100, NO-2027 Kjeller, Norway
c
Science and Technology Branch, Environment Canada, 4905 Dufferin Street, Toronto, Ontario M3 5T4, Canada
article info
Article history:
Received 21 May 2008
Received in revised form 22 July 2008
Accepted 24 July 20 08
Keywords:
Pesticides
POPs
Arctic
Legislation
Climate
abstract
Twelve year datasets of weekly atmospheric concentrations of
a
- and
g
-HCH were
compared between the two Arctic monitoring stations of Alert, Nunavut, Canada, and
Zeppelin Mountain, Svalbard, Norway. Time-series analysis was conducted with the use of
dynamic harmonic regression (DHR), wh ich provided a very good model fi t, to examine
both the seasonal behaviour in these isomers and the longer-term, underlying trends.
Strong spatial differences were not apparent between the two sites, although subtle
differences in seasonal behaviour and composition were identified. For example, the
composition of
g
-HCH to total HCH (
a
þ
g
) was greater at Zeppelin compared to Alert,
probably reflecting this site’s proximity to major use regions of lindane. Pronounced
seasonality in air concentrations for
g
-HCH was marked by a ‘spring maximum event’
(SME), confirming earlier studies. For
a
-HCH, the SME was much weaker and only evident
at Alert, whereas at Zeppelin, seasonal fluctuations for
a
-HCH were marked by elevated
concentrations in summer and lower concentrations during winter, with this pattern most
apparent for the years after 2000. We attribute this difference in spatial and temporal
patterns to the Arctic oscillation. A similar climatic pattern was not evident at either site in
the
g
-HCH data.
Seasonally adjusted, long-term trends revealed declining concentrations at both sites for
a
- and
g
-HCH over the entire time-series. Recent legislation affecting lindane use appear to
account for this decline in
g
-HCH, with little evidence of a delay or ‘lag’ between the
banning of lindane in Europe (a main source region) or Canada, and a decline in air
concentrations observed at both Arctic sites.
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
Many organochlorine (OC) pesticides are persistent
organic pollutants (POPs) that are subject to long-range
atmospheric transport (LRAT) to remote regions such as the
Arctic (e.g. Wania and Mackay, 1995, 1996; Macdonald
et al., 2005). As a consequence, POPs are targeted in Arctic
air monitoring campaigns such as the Canadian Northern
Contaminants Program (NCP) and the National Norwegian
Air Monitoring Programme, resulting in systematic weekly
sampling data extending back to the early 1990s from
monitoring sites located in the Canadian and Norwegian
Arctic.
The two principal isomers of hexachlorocyclohexane
(HCH) in technical-HCH,
a
- and
g
-HCH, have been exten-
sively measured in the Arctic, and data on air concentra-
tions exist for sampling campaigns conducted in the late
1970s and mid 1980s (e.g. Bidleman and Christensen, 1979;
*
Corresponding author.
E-mail address: c.halsall@lancaster.ac.uk (C.J. Halsall).
Contents lists available at ScienceDirect
Atmospheric Environment
journal homepage: www.elsevier.com/locate/atmosenv
1352-2310/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.atmosenv.2008.07.058
Atmospheric Environment 42 (2008) 8225–8233